Display Degrees of rotation.

[Bobw55]

I know nothing about programming a PIC or circuit design. However, give me a schematic and some breadboard and I am good to go. I want to build a display to show me the position of my antenna rotor. I am planing on using the encoder from a computer mouse. (still doing the math for how many pulses=degrees of rotation. The display would need to remember it's position when powered off. I plan on using a simple push button to reset or home the display. My question for the group is where can I find some info on a schematic or circuit design?
I would like to build this as cheaply as possible.
Thanks
Bob
http://melvinweather.com/

[Archangel]

Hello Bobw55,
here are 2 links, the first is a "special" Google link which provides you the ability to search just the forum or the entire internet. the second is one that search turned up.
http://www.google.com/custom?hl=en&c...ch&sitesearch=
http://www.picbasic.co.uk/forum/showthread.php?t=7349

[aratti]

I am planing on using the encoder from a computer mouse

Old days mouse encoders are not suitable for your application, since they have very low resolution. they will have no more than 48 pulses per turn. Additionaly you will need two channels so that you will control also direction (I am sure you will need to turn CW and CCW your antenna)

You will need also a reference pulse that will be activated when direction is at 0 degree, so you can adjust possible error in the count.

You will need at least a 360 pulses per turn, yielding a resolution of 1 degree (I am not an expert in directional antenna but one degree seems to me not enough). With an ecoder at 360 pulses per turn two channels, using a technique called "quadrature" You could achieve a resolution of 1/4 of degree, that can be doubled with a mechanical transmission yielding two turns of the encoder per turn of the antenna.

Pic mcu can handle the encoder input and display the direction of your antenna on a LCD.

The hardware is not very difficult, apart the shielding of the signal cables, the software is also not very difficult but not for a beginner for sure!

Al.

[Bobw55]

I do not plan on using the pule disc from the mouse, just the encoder from a newer one. It will be driven via a gear that would provide about 3 rev per single rev of the antenna giving at least 1000 pulses. As far as a zero point, I was figuring on using a push button for that part. I would like the display to be accurate as possible even thought +- 5 degrees is close enough.
I am still planning all of this.

Bob

[cncmachineguy]

a good source for encoders is US Digital They are very resonable on pricing and also nice folks. I have been buying from them for about 10 years. They have a wide variety, so I am sure they have something you could use. As for cost, keep in mind what it will cost to scratch something together using an old mouse. You could make it work with 48 pulses per rev, but again, it depends on what you want to spend. I would want at least 1 degree per rev, so for that you would need a 7.5 to 1 mechanical gizmo to spin the mouse encoder 7.5 times faster then the antenna. (Lego's come to mind)

The encoders I have used from US digital all have TTL level outputs, directly readable by the PIC. I am not sure if you can expect a clean transmission from the roof to inside the house. If not, you could have a pic at the antenna send RS232 signals to the house, then read them with a puter of build a unit for inside to display the position.

[cncmachineguy]

This little unit looks pretty nice
It absolute so no need to store the position, 0-5V analog output, 20 mA draw. only $40!!

[Bobw55]

I think the sensor from the mouse will work. It is the disc that I have to change out. If I can elongate the motor shaft to accommodate the disk, I can have all the pulses I need. It will create the problem of having to figure out how many per one rev of the antenna. Not too much room in the housing accept under the motor. I have also thought about using the hall sensors that are inside a CD drive motor. For me, finding a way to get sensor information from the motor is the easy part. Selecting a PIC and LCD display will be the hard part..
Keep the ideas coming!!!

Bob